1. Field of the Invention
The embodiments discussed herein relate to a semiconductor device and a method of measuring the same.
2. Background of the Related Art
There are semiconductor devices that include power semiconductor chips and that are used as power conversion devices or switching devices. For example, there is a semiconductor device in which a semiconductor chip including an insulated gate bipolar transistor (IGBT) and a semiconductor chip including a metal-oxide-semiconductor field-effect transistor (MOSFET) are connected in parallel with each other, and this semiconductor device is able to function as a switching device (for example, see Japanese Laid-open Patent Publication No. 04-354156).
Japanese Laid-open Patent Publication No. 04-354156 discusses a semiconductor device in which the emitter terminal of an IGBT and the source terminal of a MOSFET are connected to the emitter terminal of the semiconductor device at the same potential. In addition, the collector terminal of the IGBT and the drain terminal of the MOSFET are connected to an external collector terminal of the semiconductor device at the same potential. With this configuration, when an input signal is inputted to the external collector terminal of the semiconductor device, the gate of the IGBT or the MOSFET is brought in an on- or off-state, and as a result, an output signal is obtained from the emitter terminal of the semiconductor device. Consequently, a low-loss switching function is obtained.
In the semiconductor device discussed in Japanese Laid-open Patent Publication No. 04-354156, the semiconductor chips (IGBT, MOSFET) are connected in parallel with each other with respect to the emitter terminal and the external collector terminal of the semiconductor device. Thus, when characteristics such as a factory-default withstand voltage and a leakage current are measured, a semiconductor chip having the lower characteristics (having the lower withstand voltage or the larger leakage current) is measured. Namely, it is difficult to measure characteristics of the other semiconductor chip. In addition, when a forward voltage drop or the like is measured, since synthesized characteristics of a plurality of semiconductor chips appear, it is difficult to measure characteristics of an individual semiconductor chip. Thus, it is difficult to appropriately measure characteristics of the semiconductor device according to Japanese Laid-open Patent Publication No. 04-354156 after the semiconductor device is assembled.
To address this problem, external connection terminals that are electrically connected to the collector terminal and the drain terminal of the respective semiconductor chips (IGBT and MOSFET) may be used, in place of the external collector terminal of the semiconductor device. In this case, on the basis of an output signal obtained from the external emitter terminal of the semiconductor device when an input signal is inputted to one of the external connection terminals, electrical characteristics of a corresponding semiconductor chip can be measured.
To assemble a semiconductor device as described above, the individual external connection terminals need to be connected electrically to the collector terminal and the drain terminal of the respective semiconductor chips (IGBT, MOSFET). However, the connection of these external connection terminals may complicate the connection around the semiconductor device, which makes it difficult to achieve downsizing of the connection around the semiconductor device.